Five things to consider on Trump pulling out of the Paris Agreement
1. The idea that somehow, before Trump, the US was a "climate leader" is completely revisionist. We've never been climate leaders. We are the largest historical greenhouse gas emitter by far and one of the wealthiest countries in the world, yet we consistently fail to commit to emissions reductions representing our fair share of the global effort (our Paris commitment under Obama needed to be 5-6 times stronger to actually represent our fair share). We made the world weaken the Kyoto Protocol, and then we refused to ratify it. We made sure the Paris agreement was non-binding and not a treaty, and then we withdrew from it. The US has always been a roadblock to global climate action. Trump is worse but previous administrations were hardly champions.
2. The Paris Agreement is not in itself a solution to the climate crisis. It is nonbinding and commitments that countries made under the Paris framework are entirely voluntary. Those commitments are weak, adding up to a 3+ degree world compared to the goal of keeping global temperature rise under 2 degrees or, ideally 1.5. That said, like all international law, it is a tool in the toolbox and at its best could enable the kind of global cooperation that is absolutely key to solving a global problem. But in terms of pure US emissions reductions, Trump's rollbacks of domestic climate and environmental policies are more important than his withdrawal from Paris. Paris did not bind us to do anything; those policies like the Clean Power Plan were what actually would have gotten real emissions reductions. Those fights must be fought as much as the one about Paris.
3. The Paris Agreement was already a remarkably good deal for the US and other rich countries. The UN climate framework explicitly recognizes that rich countries have greater obligations than poor countries to address climate change. The Paris agreement skirts around that fact by allowing countries to make whatever pledges they want - leading to a perverse situation in which developing countries are actually pledging larger emissions reductions than the historically industrialized countries like the US, European countries, Canada, Japan, Australia, etc. This is manifestly unfair - the rich countries essentially succeeded in shifting the burden of climate change even further onto the poor. So when Trump says Paris is a bad deal for the US, he (shockingly) has no idea what he's talking about.
4. Paris was also a win for rich countries because it failed to provide any new assurances that money would be forthcoming to support climate action in developing countries. We cannot expect Bangladesh, or Rwanda, or yes, even India (which still has 300 million people without access to energy) to suddenly transition to high-tech renewable energy development pathways without some international support (financial and technological). The entire international climate regime hinges on the provision of climate finance from rich to poor countries, and Paris made zero progress on that front. Trump singled out the Green Climate Fund as a waste of taxpayer dollars, but the amount of money we've contributed ($1 billion) is miniscule compared to what we spend on other things like the military or subsidies for the fossil fuel industry - not to mention the scale of what is actually needed.
5. Let's not carelessly lump Syria and Nicaragua in with the US as the only countries in the world that aren't part of the Paris agreement. Syria has been in the midst of civil war and international sanctions. Nicaragua, more interestingly, chose not to join the agreement as an act of protest because they believed it was too weak and unfair - citing a lot of the studies and analyses put out by progressive civil society. Their refusal to join was based on entirely legitimate criticisms. Basically the opposite of Trump.